Single droplet drying of detergents: Experimentation and modelling

• Published in: Particuology 2021-10, Vol.58, p.35-47
• Main Authors: Hernandez, Borja, Mondragon, Rosa, Pinto, Mark A., Hernandez, Leonor, Julia, J. Enrique, Jarque, Juan Carlos, Chiva, Sergio, Martin, Mariano
• Format: Article
• Language: English
• Subjects: Acoustic levitator; Detergents; Drying; Single droplet
• ISSN: 1674-2001; 2210-4291
• DOI: 10.1016/j.partic.2021.01.012

[Display omitted] •Three stages are observed: free diffusion, diffusion governed by crust and boiling.•A multi-stage first principles-based model has been developed.•Droplets show a low porosity crust that governs drying during a second stage.•The second stage represents up to 25% of the total drying time in detergents.•No bursting is observed since boiling is in free convection regime. This study evaluates the single droplet drying (SDD) of detergents. Experimental data are used to validate a theoretical multistage model. The experiments are carried out in an acoustic levitator analysing six different detergent formulations at 393K. The work is completed by developing a model based on conservation equations. The model is composed of the three stages observed in the drying curve. In the first stage, an external surface drying stage occurs until the surface is saturated and the crust is formed. In the next stage, the drying rate is governed by diffusion through the pores. At the same time, the particle heats up until boiling conditions are achieved in the core of the particle. At this point, the third stage begins. In the final stage, the droplet core is in boiling conditions which are governed by the pressure drop through the crust and the concentration of salts. This model has been evaluated for the different formulations being flexible to predict the drying of different mixtures with good accuracy.